Why Screening and Early Detection for Stomach Cancer Shouldn’t Be Ignored

While stomach (or gastric) cancer can be particularly aggressive, if it is diagnosed early when the cancer is still confined to the stomach (localized), a 5-year survival rate of 72% can be reached. This underlines early detection as an ideal strategy to improve survival rates. Unfortunately, gastric cancer is often overlooked and diagnosed at later stages because most patients with early-stage disease are asymptomatic or have non-specific, subtle symptoms. This makes early detection critical and necessary, but challenging at the same time. What can individuals do to detect it early? Let’s find out.

Screening refers to the process of testing for a condition before any symptoms develop. Cancer screening can help in catching the disease in its early stages when it is often easier to treat and manage.

Be it gastric cancer or other cancer types, early detection is crucial in that it increases the chances of effective and successful treatment. This can help to save and improve the lives of cancer patients.

A person who has multiple risk factors for gastric cancer, such as certain precancerous stomach conditions or a family history of gastric cancer, has a higher chance of developing the disease. For these individuals, routine screening for gastric cancer will likely be beneficial and necessary to ensure early detection of the disease should it occur.

Doctors typically recommend that high-risk persons undergo regular screening in the form of an upper endoscopy. This test uses a thin, lighted tube called an endoscope to look at the inside of your upper gastrointestinal (GI) tract for signs of cancer. It can help to identify any precancerous or cancerous changes in the stomach lining, after which tissue samples can be removed for further testing (biopsy). An upper endoscopy is highly sensitive and specific, especially when combined with a proper biopsy follow-up for tissue diagnosis. Therefore, it is considered the gold standard detection and diagnostic test for gastric cancer. However, it is important that endoscopists are well-trained and highly experienced; early gastric cancers can be challenging to diagnose endoscopically due to the appearance of only subtle changes in the stomach lining.

In the United States and Europe as well, there are currently no guidelines or recommendations for routine gastric cancer screening in average-risk individuals. This is mostly because gastric cancer is not as common in the US, and therefore the benefits of screening may not necessarily outweigh the possible harms and costs. In particular, people who might not even have the disease would end up undergoing the invasive procedure that is an endoscopy, which remains the gold standard for gastric cancer screening.

However, in part due to the lack of routine screening, the majority of people with gastric cancer in the US are not diagnosed until they exhibit certain signs and symptoms that prompt them to seek medical attention. At this point, the cancer may have progressed to advanced stages, where the tumor has grown larger and/or spread to regions outside of the stomach, and thus has a poorer prognosis. This has sparked increasing debate on the need for routine screening for gastric cancer in Western countries, including Europe and the US.

In East Asian and South American countries, where gastric cancer is much more prevalent and incidence rates of gastric cancer are high, the implementation of organized screening programs has enabled gastric cancers to be detected at an early, more treatable stage. These programs, which generally use upper endoscopy or barium X-rays, have produced excellent results, improving early gastric cancer detection, lowering disease-specific mortality rates and ultimately increasing overall survival.

In the US, regional population-based studies have found that Asian, Black and Hispanic populations have a significantly elevated risk for gastric cancer in comparison to non-Hispanic Whites. As a result, the American Society of Gastrointestinal Endoscopy has recommended that gastric cancer screening be considered among new US immigrants above the age of 40 from high-risk endemic regions such as South Korea, Japan and South America. But, there are still no screening recommendations for other high-risk races and ethnicities in the US, particularly Hispanic and non-Hispanic Black populations. Researchers hope that by identifying racial and ethnic differences in gastric cancer incidence within the US, it can encourage efforts to tackle these differences via targeted screening in high-risk communities.

While an upper endoscopy is highly sensitive and accurate in detecting stomach cancer, the invasiveness of this procedure can put off many people, especially average-risk individuals, from ever opting for one. Not only can it cause discomfort, but in rare instances, it may cause complications such as tears in the upper GI tract and subsequent bleeding.

This has prompted mounting research in the field of non-invasive screening methods. Some clinical trials are investigating the use of protein-based biomarkers, such as Helicobacter pylori serology and serum pepsinogen, to detect gastric cancer. However, none of these protein-based biomarkers are sensitive or specific enough to be used for gastric cancer screening. Other trials are studying the use of nucleic acids, like circulating tumor DNA (ctDNA) and microRNAs (miRNAs), that are released by tumor cells into the blood as biomarkers for early gastric cancer detection. These are more sensitive and specific than protein-based tumor markers, and therefore present as promising non-invasive methods of accurately detecting the disease. Larger prospective studies are required to validate such circulating molecules as reliable biomarkers for early gastric cancer detection.

“Developing highly sensitive and specific biomarkers for gastric cancer would be integral in enhancing early disease diagnosis and survival in countries with low incidence of disease, such as Western countries, where massive population screening strategies are not cost‐effective.”

– Dr Jonathan Y. Xia and Dr Abdul Aziz Aadam, gastroenterologists from the Northwestern University Feinberg School of Medicine.

To this end, scientists in Singapore have developed a new non-invasive screening test called GASTROClear. This diagnostic test kit, which can detect both early- and late-stage gastric cancer with an accuracy of 87%, is the world’s first approved molecular blood test for early detection of gastric cancer. It works by detecting the levels of 12 miRNA biomarkers in the blood.

> Read on to find out more about GASTROClear

Gastric cancer research continues to look into the development of cheaper, less invasive screening tests that can assess the risk of healthy individuals who have not experienced any symptoms related to gastric cancer. At the same time, other studies are investigating new endoscopic technologies and the use of Artificial Intelligence (AI) as a companion technology to help endoscopists detect gastric cancer early. Altogether, these advancements hold the potential for earlier and improved gastric cancer detection, which can possibly save more lives. The earlier people receive a gastric cancer diagnosis and treatment, the higher their chances of successful treatment and a better prognosis.